Network-based service users may provide credentials to the service for use in authenticating the identity of the user and determining that the user is authorized to access various resources of the service. For example, users of these network-based services may provide credentials such as a username and password to a computing device before the service can be accessed. For greater security, the user may enter the user's credentials each time the user interacts with a different computing device, or repeatedly accesses the same device, in order to access the service.